Bug 197015

Summary: [JSC] Optimize cases of Array.prototype.join/toString on huge empty arrays which result into one-character repeats
Product: WebKit Reporter: Yacine Bandou <bandou.yacine>
Component: JavaScriptCoreAssignee: Nobody <webkit-unassigned>
Status: NEW    
Severity: Normal CC: bfulgham, ews-watchlist, fpizlo, guijemont, keith_miller, loic.yhuel, mark.lam, msaboff, olivier.blin, saam, ticaiolima, webkit-bug-importer, ysuzuki, zan
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
Attachments:
Description Flags
Patch
none
Patch
none
Patch bandou.yacine: review?, bandou.yacine: commit-queue?

Yacine Bandou
Reported 2019-04-17 09:30:22 PDT
Add a fast case in Array.prototype.join when the array is empty and it uses array_storage indexingType and the separator length is less than 2. Use the same optimisation that is used in the case of UNDECIDED indexingType, in order allocate the final string in one step, instead of appending in a loop which consumes additional temporary memory.
Attachments
Patch (4.73 KB, patch)
2019-04-17 10:00 PDT, Yacine Bandou 		no flags
DetailsFormatted DiffDiff
Patch (4.75 KB, patch)
2019-04-17 10:23 PDT, Yacine Bandou 		no flags
DetailsFormatted DiffDiff
Patch (6.65 KB, patch)
2019-05-10 09:33 PDT, Yacine Bandou 		bandou.yacine: review?
bandou.yacine: commit-queue?
DetailsFormatted DiffDiff
Show Obsolete (2) View All Add attachment proposed patch, testcase, etc.
Yacine Bandou
Comment 1 2019-04-17 10:00:23 PDT
Created attachment 367638 [details] Patch
Yacine Bandou
Comment 2 2019-04-17 10:23:02 PDT
Created attachment 367645 [details] Patch
Olivier Blin
Comment 3 2019-04-18 00:20:26 PDT
For reference, this has been done to optimize the memory consumption of the "CPU Memory Allocation" YouTube test here: https://ytlr-cert.appspot.com/2019/main.html?test_type=functional-test
Yusuke Suzuki
Comment 4 2019-04-18 00:49:58 PDT
Comment on attachment 367645 [details] Patch Can you add tests?, like 1. simple test 2. array storage with some element 3. array storage + accessors 4. and so on
Yacine Bandou
Comment 5 2019-05-10 09:33:43 PDT
Created attachment 369554 [details] Patch
Radar WebKit Bug Importer
Comment 6 2022-07-01 15:39:09 PDT
<rdar://problem/96318246>
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